package org.javacore.thread;

import java.util.ArrayList;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
/**
 * Created by BYSocket on 2015/11/2.
 *
 * Copyright [2015] [Jeff Lee]
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @author Jeff Lee
 * @since 2015-11-2 18:58:36 Callable接口的使用 --- 实现带返回值的任务
 */

// Callable实现类task，指定其类型参数
class TaskWithResult implements Callable<String> {

	private int id;

	public TaskWithResult(int id) {
		this.id = id;
	}

	@Override
	public String call() throws Exception {
		return "result of TaskWithResult " + id;
	}
}

public class CallableDemo {
	public static void main(String[] args) {
		// 创建一个新的线程池
		ExecutorService exec = Executors.newCachedThreadPool();
		// Callable实现类task的返回结果集
		ArrayList<Future<String>> results = new ArrayList<>();
		for (int i = 0; i < 5; i++)
			results.add(exec.submit(new TaskWithResult(i)));// 使用submit来启动Tasks

		// 异步计算的结果
		for (Future<String> fs : results)
			try {
				// get阻塞，直至获取结果
				System.out.println(fs.get());
			} catch (InterruptedException e) {
				System.out.println(e);
				e.printStackTrace();
			} catch (ExecutionException e) {
				System.out.println(e);
				e.printStackTrace();
			} finally {
				exec.shutdown();
			}
	}
}